Sub-orthogonal Self-Jammer Cancellation Circuit for RFID Readers
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Solution Overview
Problem
RFID readers face interference from self-jammer signals, which degrade the quality of received RF signals from tags due to shared antenna usage, and existing solutions like signal attenuation affect both self-jammer and tag signals, leading to undesirable outcomes.
Innovation Solution
A sub-orthogonal self-jammer cancellation circuit generates distinct phase variants of the transmit signal, selects appropriate phase variants, and combines them to create a canceling signal equal in amplitude but opposite in phase to the self-jammer signal, reducing its amplitude and enhancing the signal-to-noise ratio for better tag signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If signal attenuation is used to mitigate self-jammer signal, then self-jammer interference is reduced, but tag signal strength is also reduced
Solution Approach 1:
The patent extracts and removes only the harmful self-jammer signal component from the received signal while preserving the desired tag signal. This is achieved through self-jammer cancellation circuitry that specifically targets and eliminates the self-jammer component without affecting the tag signal, resolving the contradiction between reducing interference and maintaining signal quality.
Solution Approach 2:
The patent converts the harmful self-jammer signal into a useful cancellation signal by generating a replica of the self-jammer and combining it with the received signal to cancel out the interference. This transforms the harmful effect into a beneficial process that improves overall signal quality while preserving the tag signal.
2Object-affected harmful factors
If orthogonal signals are used for self-jammer cancellation, then self-jammer signal is cancelled, but power consumption increases
Solution Approach 1:
The patent changes the phase parameter of the transmit signal to create phase variants that are sub-orthogonal rather than fully orthogonal. By adjusting the phase difference between signals, the system achieves effective self-jammer cancellation while reducing the power consumption associated with generating and processing fully orthogonal signals.
Solution Approach 2:
The patent uses sub-orthogonal signals instead of fully orthogonal signals, applying partial action to achieve sufficient cancellation performance. This partial approach reduces the computational and power resources needed while still effectively mitigating the self-jammer interference, balancing performance with energy efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively cancels self-jammer signals, increasing the receiver's signal-to-noise ratio and sensitivity while minimizing power consumption, thus improving the overall performance of RFID readers.
Implementation Method 1
a canceling signal comprising a combination of the selected phase variants is substantially opposite in phase to the self-jamming signal
Data Source
AI summary
RFID readers configured to transmit a radio frequency signal include a sub-orthogonal self-jammer cancellation circuit that generates two or more distinct phase variants of the transmit signal, selects two of the phase variants with a vector projection of one of the selected phase variants on another of the selected phase variants being substantially greater than zero such that a canceling signal comprising a combination of the at least two phase variants is substantially opposite in phase to a self-jamming signal, and selects amplitudes for the at least two selected phase variants such that the canceling signal is substantially equal in amplitude to the self-jamming signal. The canceling signal is then combined with the self-jamming signal to reduce the amplitude of an RF signal received by a receive circuit.